JP2016053394A - Flow rate controller and sphygmomanometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate controller which controls a flow rate of a fluid by opening/closing a solenoid valve by a drive voltage, and which can set the drive voltage of the solenoid valve within a range between a flow start point voltage and a limit voltage with good accuracy.SOLUTION: A correlation storage unit 251 stores a correlation between a flow start point voltage in which a fluid starts to flow through a sample solenoid valve and a limit voltage in which the sample solenoid valve becomes fully open, regarding the sample solenoid valve having substantially the same characteristics as that of a solenoid valve 233. When a control unit 201 starts control of a flow rate of the fluid, it changes a drive voltage of the solenoid valve 233, and acquires the drive voltage at the time when a flow rate detection unit detects the flow start of the fluid as a flow start point voltage. Based on the flow start point voltage of the solenoid valve 233, by using the correlation about the sample solenoid valve, the limit voltage in which the solenoid valve becomes fully open is converted and acquired. Then, the drive voltage of the solenoid valve 233 is set within the range between the flow start point voltage and the limit voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flow rate control device, and more particularly to a flow rate control device that controls a flow rate of a fluid by an electromagnetic valve.

  The present invention also relates to a sphygmomanometer equipped with such a flow control device.

  Conventionally, as a sphygmomanometer, as shown in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 6-245911), a cuff for blocking a measurement site by controlling a flow rate of air as a fluid by a solenoid valve ( Exactly, what adjusts the pressure of the fluid bag in the cuff is known.

JP-A-6-245911

  This type of sphygmomanometer uses a normally open type (valve that fully opens the flow path when de-energized) as a solenoid valve for flow control, and applies a drive voltage to the solenoid of the solenoid valve during operation. In many cases, the cross-sectional area of the flow path is adjusted by energizing and moving the valve body by the electromagnetic force of the solenoid. When not energized, the solenoid valve is fully opened, so the cuff is not pressurized. This is to ensure the safety of the subject when the power is turned off (energization is stopped) in the event of an accident.

  In general, the flow rate versus drive voltage characteristics of such a solenoid valve is such that if the effective drive voltage (and hence the energization current) is sufficiently high, the solenoid valve is fully closed and the flow rate becomes zero. When the drive voltage decreases to a certain value (referred to as “flow start point voltage”), the solenoid valve opens and fluid starts to flow. When the drive voltage is further decreased, the flow rate is gradually increased. When the drive voltage is lower than the limit (referred to as “limit voltage”), the solenoid valve is fully opened and the flow rate is extremely increased (that is, the flow rate is increased). It becomes out of control.) Therefore, the driving voltage of the solenoid valve during operation needs to be set within a range between the flow start point voltage and the limit voltage (this is appropriately referred to as an “effective setting range”).

  Here, when measuring a sphygmomanometer, the cuff pressure is often made higher than the highest blood pressure (systolic blood pressure) of the person to be measured, and the pulse wave at the measurement site is often observed in the subsequent decompression process. In that case, at the start of pressure reduction, it is desirable to set the drive voltage of the solenoid valve in the vicinity of the limit voltage within the effective setting range to increase the exhaust gas flow rate and perform pressure reduction quickly.

  However, the limit voltage of the solenoid valve may change due to factors such as cuff pressure (pressure upstream of the solenoid valve), ambient temperature, and variations among individual products. For this reason, when it is going to set the drive voltage of a solenoid valve in the vicinity of a limit voltage within an effective setting range, there is a possibility that it will fall below the limit voltage of the solenoid valve. Once the drive voltage of the solenoid valve falls below the limit voltage, the flow rate is extremely increased and the cuff pressure is lowered at a stretch, which causes a problem that a sufficient pressure range for observing the pulse wave cannot be secured. In particular, inexpensive solenoid valves tend to have a narrow effective setting range, and this problem becomes serious.

  Accordingly, an object of the present invention is to provide a flow rate control device that controls the flow rate of a fluid by opening and closing a solenoid valve with a drive voltage, which can accurately set the drive voltage of the solenoid valve within an effective setting range. There is.

  Another object of the present invention is to provide a sphygmomanometer having such a flow rate control device so that the time required for blood pressure measurement can be shortened.

  The present inventors have found that the drive voltage for opening and closing the solenoid valve has a correlation between the flow starting point voltage at which fluid starts to flow through the solenoid valve and the limit voltage at which the solenoid valve is fully opened. Was created based on.

In order to solve the above problems, the flow control device of the present invention is:
A flow rate control device that controls the flow rate of fluid by opening and closing a solenoid valve with a drive voltage,
A flow rate detection unit for detecting the flow rate of the fluid flowing through the solenoid valve;
For a sample solenoid valve having substantially the same characteristics as the solenoid valve, the correlation between the starting point voltage at which fluid starts flowing through the sample solenoid valve and the limit voltage at which the sample solenoid valve is fully opened is stored. A correlation storage unit;
When starting the control of the flow rate of the fluid, the drive voltage of the solenoid valve is changed, and the drive voltage when the flow rate detection unit detects the start of the flow of the fluid is obtained as a flow start point voltage. Based on the correlation with respect to the sample solenoid valve according to the flow start point voltage, the limit voltage at which the solenoid valve is fully opened is calculated, and then the drive voltage of the solenoid valve is set as the flow start point voltage. And a control unit that is set within a range between the limit voltage.

  Here, the “solenoid valve” may be either a normally open type or a normally closed type.

  The “sample solenoid valve having substantially the same characteristics” as the solenoid valve means one having substantially the same flow rate versus drive voltage characteristics as the solenoid valve for controlling the flow rate of the fluid. “Substantially the same” means that differences in characteristics between individuals due to manufacturing variations are allowed. For example, the “sample solenoid valve” may be another individual having the same model number as the solenoid valve that controls the flow rate of the fluid, or the solenoid valve itself. Further, there may be a plurality of “sample solenoid valves”.

  As for “flow start point voltage” and “limit voltage”, there are a case where the flow start point voltage is higher than the limit voltage and a case where the flow start point voltage is lower than the limit voltage, depending on the type of the solenoid valve.

  In the flow control device according to the present invention, the correlation storage unit is configured to determine whether the sample solenoid valve has a flow start point voltage at which a fluid starts to flow through the sample solenoid valve, and the sample solenoid valve has substantially the same characteristics as the solenoid valve to be driven. The correlation between the fully opened limit voltage is stored. When starting the control of the flow rate of the fluid, the control unit changes the drive voltage of the solenoid valve, and obtains the drive voltage when the flow rate detection unit detects the start of the flow of the fluid as the flow start point voltage (note that The change of the driving voltage at this time is performed in the vicinity of the flow starting point voltage, that is, at a position sufficiently away from the limit voltage). Next, the control unit converts and obtains a limit voltage at which the electromagnetic valve is fully opened based on the correlation with respect to the sample electromagnetic valve in accordance with the flow starting point voltage of the electromagnetic valve. Thereafter, the control unit sets the drive voltage of the solenoid valve within a range (effective setting range) between the flow start point voltage and the limit voltage, and opens and closes the solenoid valve with the drive voltage, Control fluid flow.

  As described above, in the flow rate control device of the present invention, the limit voltage at which the solenoid valve is fully opened is calculated using the correlation with respect to the sample solenoid valve, so that the drive voltage of the solenoid valve is effective. It can be set accurately within the setting range.

  In the flow control device of one embodiment, the correlation about the sample solenoid valve stored in the correlation storage unit includes a relationship when a plurality of fluid pressures are set to be variable. To do.

  Here, the “pressure” of the fluid means a differential pressure between the upstream side and the downstream side applied to the sample solenoid valve.

  When the pressure of the fluid changes, the force of the fluid pushing the valve body of the solenoid valve changes against the electromagnetic force of the solenoid included in the solenoid valve (or the sample solenoid valve). For this reason, even if the effective drive voltage is the same, the flow rate of the fluid passing through the electromagnetic valve changes. Along with this, the correlation between the flow starting point voltage and the limit voltage may change. Therefore, in the flow control device of this embodiment, the correlation for the sample electromagnetic valve stored in the correlation storage unit includes a relationship when a plurality of fluid pressures are set to be variable. As a result, the limit voltage of the solenoid valve is a value that takes into account the pressure of the fluid. Therefore, the driving voltage of the solenoid valve can be set with higher accuracy within the effective setting range.

In the flow control device of one embodiment,
A pressure sensor for detecting the pressure of the fluid;
The control unit
At the start of control, the pressure of the fluid is detected by the pressure sensor,
When the pressure of the fluid at the start of control takes a value other than the plurality of pressures giving the correlation stored in the correlation storage unit, based on the correlation corresponding to the plurality of pressures, By interpolating or extrapolating, obtain the correlation between the flow start point voltage corresponding to the pressure of the fluid at the start of control and the limit voltage,
When the limit voltage is obtained by conversion based on the flow start point voltage of the solenoid valve, the obtained correlation is used.

  In the flow control device of this embodiment, the control unit detects the pressure of the fluid by the pressure sensor at the start of control. When the pressure of the fluid at the start of the control takes a value other than the plurality of pressures that give the correlation stored in the correlation storage unit, the control unit performs the correlation corresponding to the plurality of pressures. Based on the relationship, the correlation between the flow start point voltage corresponding to the pressure of the fluid at the start of control and the limit voltage is obtained by interpolation or extrapolation. And when calculating | requiring and obtaining the said limit voltage based on the said flow start point voltage of the said solenoid valve, the calculated | required correlation is used. Thereby, even when the pressure of the fluid at the start of the control takes a value other than the plurality of pressures giving the correlation stored in the correlation storage unit, the driving voltage of the solenoid valve is reduced. It can be set accurately within the effective setting range.

In the flow control device of one embodiment,
The control unit
Detecting the current pressure of the fluid by the pressure sensor during the control period;
When the current pressure of the fluid changes from the pressure at the start of control, the current flow starting point voltage and the limit voltage for the solenoid valve are converted and obtained based on the correlation corresponding to the plurality of pressures. It is characterized by that.

  In the flow control device of this embodiment, the control unit detects the current pressure of the fluid by the pressure sensor. When the current pressure of the fluid changes from the pressure at the start of control, the control unit determines the current flow start voltage and limit voltage for the solenoid valve based on the correlation corresponding to the plurality of pressures. Is calculated. Thereby, even if the pressure of the fluid changes during the control period, the driving voltage of the solenoid valve can be set within the effective setting range with high accuracy in real time.

  In one embodiment, the correlation for the sample solenoid valve includes a relationship when a plurality of ambient temperatures are set.

  Here, “ambient temperature” means the temperature of the environment surrounding the sample solenoid valve (or solenoid valve).

  When the ambient temperature changes, the electrical resistance of the solenoid included in the solenoid valve (or sample solenoid valve) changes. For this reason, even if the effective drive voltage is the same, the energization current to the solenoid valve changes and the opening degree of the solenoid valve changes. Along with this, the correlation between the flow starting point voltage and the limit voltage may change. Therefore, in the flow control device of this embodiment, the correlation for the sample solenoid valve includes a relationship when a plurality of ambient temperatures are set. As a result, the limit voltage of the solenoid valve takes into account the ambient temperature. Therefore, the driving voltage of the solenoid valve can be set with higher accuracy within the effective setting range.

In the flow control device of one embodiment,
A temperature sensor for detecting the ambient temperature of the solenoid valve;
The control unit
The current ambient temperature of the solenoid valve is detected by the temperature sensor during the control period,
When the current ambient temperature of the solenoid valve changes from the ambient temperature at the start of control, the current flow start point voltage and the limit voltage for the solenoid valve are calculated based on the correlation corresponding to the plurality of ambient temperatures. It is obtained by conversion.

  In the flow control device of this embodiment, the control unit detects the current ambient temperature of the solenoid valve by the temperature sensor during the control period. When the current ambient temperature of the solenoid valve changes from the ambient temperature at the start of control, the control unit determines the current flow start point for the solenoid valve based on the correlation corresponding to the plurality of ambient temperatures. Obtained by converting voltage and limit voltage. As a result, even when the ambient temperature of the solenoid valve changes during the control period, the drive voltage of the solenoid valve can be accurately set in real time within the effective setting range.

The sphygmomanometer of this invention is
A cuff to compress the measurement site;
A solenoid valve for adjusting the pressure of the cuff;
The flow rate control device is provided.

  According to the sphygmomanometer of the present invention, for example, at the time of starting decompression after the cuff pressure is once higher than the highest blood pressure (systolic blood pressure) of the person to be measured, the drive voltage of the electromagnetic valve is within the effective setting range. It can be set accurately in the vicinity. Therefore, it is possible to increase the exhaust flow rate at the start of pressure reduction and perform quick pressure reduction. As a result, the time required for blood pressure measurement can be shortened. Moreover, since the drive voltage of the solenoid valve does not fall below the limit voltage, it is possible to avoid a situation in which the cuff pressure drops at a stretch during blood pressure measurement, resulting in a measurement error. Moreover, it becomes easy to employ an inexpensive solenoid valve that tends to have a narrow effective setting range.

  In particular, when the correlation for the sample solenoid valve includes a relationship when a plurality of ambient temperatures are set, the limit voltage of the solenoid valve calculated by the control unit takes the ambient temperature into account. Will be. In addition, blood pressure measurement is often performed in a relatively short period (typically about 1 minute) so that it is not necessary to consider changes in the ambient temperature T. In that case, the drive voltage of the solenoid valve can be accurately set within the effective setting range without providing a temperature sensor.

  As is clear from the above, according to the flow control device of the present invention, the drive voltage of the solenoid valve can be set with high accuracy within the effective setting range.

  Moreover, according to the blood pressure monitor of the present invention, the time required for blood pressure measurement can be shortened. In addition, it is possible to avoid a situation in which the cuff pressure decreases at a stretch during blood pressure measurement, resulting in a measurement error.

It is a figure which shows the block configuration of the flow control apparatus of one Embodiment of this invention. FIG. 2A is a diagram showing the waveform of the drive voltage applied to the electromagnetic valve by the flow rate control device. FIG. 2B is a diagram showing the relationship between the drive voltage (effective value) and the energizing current (effective value) for the solenoid valve. It is a figure which shows the structure of the said solenoid valve. It is a figure which shows the state of the valve body vicinity at the time of the action | operation of the said solenoid valve. It is a figure which shows the flow volume versus drive voltage characteristic (QV characteristic) in the ambient temperature T == 23 degreeC of the said solenoid valve. It is a figure which shows the QV characteristic in ambient temperature T == 45 degreeC of the said solenoid valve. It is a figure which shows the QV characteristic in ambient temperature T == 5 degreeC of the said solenoid valve. For five sample solenoid valves having substantially the same characteristics as the solenoid valve to be controlled, the correlation between the flow start point voltage Vs and the limit voltage Vf under the condition that the upstream pressure P is set to 300 mmHg is shown. FIG. For five sample solenoid valves having substantially the same characteristics as the solenoid valve to be controlled, the correlation between the flow start point voltage Vs and the limit voltage Vf under the condition where the upstream pressure P is set to 150 mmHg is shown. FIG. It is a figure which shows the processing flow by the control part of the said flow control apparatus. It is a figure which shows typically the method of converting and calculating | requiring the present flow starting point voltage Vs and the limit voltage Vf when the pressure of the fluid with respect to the said solenoid valve changes during the control period. When the pressure at the start of control takes a value between 300 mmHg and 150 mmHg to which the correlation stored in the correlation storage unit is given, a flow corresponding to the pressure of the fluid at the start of control is obtained by interpolation. It is a figure which shows typically the method of calculating | requiring the correlation between the starting point voltage Vs and the limit voltage Vf. It is a figure which shows the external appearance of the electronic blood pressure monitor of one Embodiment of this invention. It is a figure which shows the schematic block configuration of the said electronic blood pressure monitor. It is a figure which shows the block structure of the principal part regarding control of the solenoid valve of the said electronic blood pressure monitor. It is a figure which shows the flow of the blood pressure measurement by the said electronic blood pressure monitor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 illustrates the structure of the solenoid valve 233 to be controlled by the flow control device of one embodiment of the present invention. This electromagnetic valve 233 is of a normally open type, for example, mounted on an “upper arm blood pressure monitor HEM-7320F” manufactured by OMRON Healthcare.

  The electromagnetic valve 233 includes a U-shaped yoke 273, a substantially cylindrical core 274 fixed to a central wall 237a of the yoke 273, a coil spring 275 as an urging portion, and a substantially round bar-shaped plunger. (Movable iron core) 276, a bobbin 280 made of a nonmagnetic plastic material housed in the yoke 273, and a substantially rectangular plate-shaped yoke lid 290 for closing the open end of the yoke 273. The yoke 273, the core 274, the plunger 276, and the yoke lid 290 are made of a magnetic material so as to constitute a magnetic circuit during operation.

  The bobbin 280 is integrally provided with a cylindrical portion 281 around which a solenoid coil 279 is wound and a pair of end plates 282 and 283. The pair of end plates 282 and 283 are sandwiched between the central wall of the yoke 273 and the yoke lid 290 and fixed to the yoke 273.

  The core 274 passes through the central wall 237 a of the yoke 273 and extends partway through the cylindrical portion 281 of the bobbin 280. A circulation hole 270 is formed in the core 274 so as to penetrate the fluid from the outer end 270e toward the inner end 270f in the axial direction.

  The plunger (movable iron core) 276 is accommodated in the cylindrical portion 281 of the bobbin 280 so as to be slidable in the axial direction. A valve body 261 made of an elastic material such as rubber is attached to one end (end portion of the core 274 on the side facing the flow hole 270) 276e.

  The coil spring 275 is contracted between the core 274 and the plunger 276 to urge the plunger 276 in a direction away from the core 274.

  When the solenoid coil 279 is in a non-energized state and is not in operation, the valve body 261 provided at one end 276e of the plunger 276 is moved by the urging force of the coil spring 275 as shown in FIG. (The end on the side facing 261) is separated from 270f. Thus, the gap Δ between the inner end 270f of the core 274 and the valve body 261 is in a fully open state. The other end 276f of the plunger 276 protrudes outward from the yoke lid 290 and is brought into contact with and engaged with the end 281f of the cylindrical portion 281 of the bobbin 280. The fluid is supplied from an upstream pressure source (not shown) to the outer end 270e of the core 274, passes through the flow hole 270 and the above-described gap Δ, and passes through the cylindrical portion 281 (external environment) of the downstream bobbin 280. A fluid outlet (not shown) that is open to the

  When the solenoid coil 279 is energized, the valve element 261 is moved in the bobbin 280 together with the plunger 276 against the urging force of the coil spring 275 by the magnetic force generated by the solenoid coil 279 as shown in FIG. . As a result, the gap Δ between the inner end 270f of the core 274 and the valve element 261 is reduced, and the flow rate Q of the fluid flowing through the flow hole 270 is adjusted.

For example, a drive voltage (peak value V ₀ ) having a rectangular pulse waveform as shown in FIG. 2A is applied to the solenoid coil 279. The duty ratio (t1 / t2) of the pulse wave is changed by PWM (pulse width modulation), and the effective value V of the drive voltage is variably set. As shown in FIG. 2B, the effective value I of the energization current for the solenoid coil 279 is proportional to the effective value V of the drive voltage. Hereinafter, the effective value of the drive voltage is simply referred to as drive voltage V. The effective value of the energization current is simply referred to as the energization current I.

  This solenoid valve 233 exhibits flow rate versus drive voltage characteristics (QV characteristics) as shown in FIGS. 5 to 7 for air as a fluid (the drive voltage V is on the horizontal axis and the flow rate Q is on the vertical axis). .) Further, the pressure of air as a fluid supplied from the upstream side to the electromagnetic valve 233 (the outer end 270e of the flow hole 270) is 30 mmHg, 150 mmHg, 300 mmHg (which is a differential pressure with respect to the atmospheric pressure on the downstream side). The same applies to the following). In addition, since the object whose flow rate is to be controlled is not limited to air, it is hereinafter referred to as “fluid” as appropriate.

As shown in FIG. 5, at the ambient temperature T = 23 ° C. (normal temperature), the QV characteristics are expressed by curves C ₃₀ , C ₁₅₀ , and the upstream pressure P with respect to the solenoid valve increases as 30 mmHg, 150 mmHg, and 300 mmHg. It shifted to the upper right as indicated by C _300. This is because, for example, when the pressure P on the upstream side (left side) in FIG. 4 increases, the force of the fluid that presses the valve element 261 increases against the electromagnetic force of the solenoid coil 279. For this reason, when the upstream pressure P increases, the flow rate Q of the fluid passing through the electromagnetic valve 233 increases even if the effective drive voltage V is the same. In other words, in order to maintain the same flow rate Q when the upstream side (left side) pressure P increases, the energizing current I (and hence the magnetic force) to the solenoid coil 279 is increased, and the valve element 261 is moved to the plunger 276. At the same time, it must be pushed more strongly upstream. In this example, as the upstream pressure P increases to 30 mmHg, 150 mmHg, and 300 mmHg, the flow starting point voltage Vs at which the fluid begins to flow is approximately 2.5 V, 2.9 V, and 3.3 V (respectively indicated by ↑). As the voltage increases, the limit voltage Vf at which the electromagnetic valve 233 is fully opened increases in order of approximately 1.1 V, 1.7 V, and 2.1 V (respectively indicated by Δ).

  As shown in FIG. 6, when the ambient temperature T = 45 ° C. (high temperature), the QV characteristic shifts to the right as a whole with respect to the characteristics at the ambient temperature T = 23 ° C. (room temperature) in FIG. To do. This is because the electrical resistance of the solenoid coil 279 increases as the ambient temperature T increases, so that the drive voltage V must be increased in order to maintain the same energization current I. In this example, when the upstream pressure P is 30 mmHg, 150 mmHg, and 300 mmHg, the flow start point voltage Vs is approximately 2.8 V, 3.4 V, and 3.9 V (respectively indicated by ↑), and the limit voltage Vf is The voltage is generally 1.3 V, 1.9 V, and 2.5 V (represented by Δ marks).

  On the other hand, as shown in FIG. 7, when the ambient temperature T = 5 ° C. (low temperature), the QV characteristic is as a whole with respect to the characteristics at the ambient temperature T = 23 ° C. (normal temperature) in FIG. Shift to the left. This is because the electrical resistance of the solenoid coil 279 decreases as the ambient temperature T decreases, and the drive voltage V must be reduced in order to maintain the same energization current I. In this example, when the upstream pressure P is 30 mmHg, 150 mmHg, and 300 mmHg, the flow starting point voltage Vs is approximately 2.4 V, 2.8 V, and 3.0 V (respectively indicated by ↑), and the limit voltage Vf is The voltage is approximately 1.1 V, 1.6 V, and 2.0 V (represented by Δ marks).

  As can be seen from FIGS. 5 to 7, when the upstream pressure P with respect to the electromagnetic valve 233 and the ambient temperature T change, both the flow start point voltage Vs and the limit voltage Vf change. Here, the inventor of the present invention uses the solenoid valve 233 and the solenoid valve having substantially the same QV characteristics as these (referred to as “sample solenoid valve”) as the flow start point voltage Vs and the limit voltage Vf. We found that there is a common correlation between them.

  8 and 9 show that the upstream side pressure P was set to 300 mmHg and 150 mmHg for five sample solenoid valves having substantially the same QV characteristics (in this example, the same model number) as the solenoid valve 233. The correlation between the flow start point voltage Vs and the limit voltage Vf under the conditions is shown as a scatter diagram. In these figures, each symbol represents a data point of one sample solenoid valve at an ambient temperature T = 23 ° C. (normal temperature). Each □ represents a data point of one sample solenoid valve at an ambient temperature T = 2 ° C. (low temperature). Each Δ mark represents a data point of one sample solenoid valve at an ambient temperature T = 50 ° C. (high temperature).

As can be seen from FIG. 8, in the case of the upstream pressure P = 300 mmHg, when the ambient temperature T is set with a plurality of variables of 2 ° C., 23 ° C., and 50 ° C., the above five sample solenoid valves are used. The flow starting point voltage Vs and the limit voltage Vf change in a positive correlation. In this example, this correlation is approximated by a line segment RL ₃₀₀ (hereinafter, referred to as “correlation RL ₃₀₀ ” as appropriate). Further, as can be seen from FIG. 9, when the upstream pressure P = 150 mmHg, when the ambient temperature T is set to be a plurality of variables such as 2 ° C., 23 ° C., and 50 ° C., the above five sample electromagnetics The flow starting point voltage Vs and the limit voltage Vf for the valve change with a positive correlation. In this example, this correlation is approximated by a line segment RL ₁₅₀ (hereinafter referred to as “correlation RL ₁₅₀ ” as appropriate).

Thus, when the upstream pressure P is set to 300 mmHg and 150 mmHg, when the ambient temperature T changes, the flow start point voltage Vs and the limit voltage Vf have a positive correlation RL ₃₀₀ , RL ₁₅₀ . Show. Therefore, if the flow starting point voltage Vs of the solenoid valve 233 is known, the limit voltage Vf of the solenoid valve 233 can be converted and obtained using these correlations regardless of the ambient temperature T. For example, when the upstream pressure P is 300 mmHg, if the flow starting point voltage Vs of the electromagnetic valve 233 is 3.10 V as shown by the broken line A1 in FIG. 8, the electromagnetic valve 233 is shown by the broken line A2 in FIG. Can be determined to be about 1.10V. In this case, the range (effective setting range) in which the drive voltage V for the electromagnetic valve 233 should be set is about 1.10V to 3.10V. In FIG. 8, a point corresponding to Vs = 3.10 V and Vf = 1.10 V in the line segment RL ₃₀₀ is represented by reference numeral D1.

As can be seen from a comparison between FIG. 8 and FIG. 9, when the pressure P changes from ₃₀₀ mmHg to 150 mmHg, the line segment RL ₁₅₀ shifts to the left with respect to the line segment RL ₃₀₀ . The reason for this is considered that the flow start point voltage Vs is greatly influenced by the upstream pressure P as compared with the limit voltage Vf.

  FIG. 1 shows a block configuration of a flow control device 200 according to an embodiment of the present invention based on the discovery that there is a correlation between the flow start point voltage Vs and the limit voltage Vf of the electromagnetic valve 233. In order to control the flow rate of fluid by the electromagnetic valve 233, the flow control device 200 includes a correlation storage unit 251, a control unit 201, a duty calculation unit 202, a pulse generation unit 203, a valve drive circuit 230, A power supply unit 253, a pressure sensor 231 and a flow rate sensor 232 as a flow rate detection unit are provided.

  The solenoid valve 233 is interposed between a pipe 238 connected to the fluid inlet 220 and a pipe 239 connected to the fluid outlet 240. The fluid is supplied from an upstream pressure source (not shown) to the solenoid valve 233 (the outer end 270e of the flow hole 270) through the fluid inlet 220 and the pipe 238. The fluid that has passed through the electromagnetic valve 233 is released to the external environment (at atmospheric pressure) through the pipe 239 and the fluid outlet 240. Note that the pressure loss due to the pipes 238 and 239 is negligible.

  The pressure sensor 231 detects the pressure of the fluid passing through the pipe 238. As this pressure sensor 231, a known piezoresistive pressure sensor, for example, a commercially available pressure sensor manufactured by Mitsumi Electric Co., Ltd. (for example, product number MMR901XA, operating pressure range 0 to 40 kPa (300 mmHg)) or the like can be used. .

  The flow rate sensor 232 detects the flow rate of the fluid passing through the pipe 238. As this flow sensor 232, for example, a commercially available MEMS (Micro Electro Mechanical Systems) flow sensor (D6F-02A1-110, flow detection range 0 to 2 L / min) manufactured by OMRON Corporation can be used.

The correlation storage unit 251 sets a flow starting point voltage Vs at which a fluid starts to flow through the sample solenoid valve and a limit at which the sample solenoid valve is fully opened with respect to the drive voltage of the sample solenoid valve having substantially the same characteristics as the solenoid valve 233 to be controlled. The correlation between the voltage Vf is stored. In this example, formulas of line segments RL ₃₀₀ and RL ₁₅₀ representing the correlation shown in FIGS. 8 and 9 are stored. In this example, the correlation storage unit 251 includes an EEPROM (Electrically Programmable Read Only Memory), but may alternatively include a RAM (Random Access Memory), a memory card, or an SSD (Solid State Drive). Good.

The power supply unit 253 supplies power to each unit of the flow control device 200. In particular, the power supply unit 253 supplies a DC voltage (having a magnitude corresponding to V ₀ in FIG. 2A) to the duty calculation unit 202 and the valve drive circuit 230. In this example, it is assumed that the DC voltage V ₀ = 6V.

The control unit 201 controls the overall operation of the flow control device 200. In particular, the control unit 201 determines that the flow rate Q of the fluid passing through the electromagnetic valve 233 becomes a target flow rate (Q _TARGET ) based on the outputs of the pressure sensor 231 and the flow rate sensor 232. The drive voltage V to be applied to the solenoid coil 279) is calculated and determined. In this example, the control unit 201 includes a CPU (Central Processing Unit), and executes processing according to a program and data stored in a memory (not shown).

The duty calculation unit 202 compares the drive voltage V determined by the control unit 201 with the DC voltage V ₀ (= 6 V) supplied by the power supply unit 253, and the drive voltage V determined by the control unit 201 by the valve drive circuit 230. Is obtained, the duty ratio (t1 / t2) for creating a rectangular pulse waveform as shown in FIG.

  The pulse generator 203 generates a rectangular pulse waveform having the duty ratio (t1 / t2) calculated by the duty calculator 202.

  The functions of the duty calculator 202 and the pulse generator 203 are realized by the processing of the CPU described above.

The valve drive circuit 230 includes a switching element (not shown) for turning on and off the DC voltage V ₀ (= 6 V) from the power supply unit 253. This switching element is ON / OFF controlled by the pulse generator 203 with a rectangular pulse waveform (known PWM control). As a result, the valve drive circuit 230 outputs a rectangular pulse waveform as shown in FIG. 2A as the drive voltage (effective value V) to be applied to the electromagnetic valve 233. The duty ratio of the output pulse waveform is (t1 / t2), and the peak value is V ₀ = 6V.

  FIG. 10 shows a processing flow in which the flow rate Q of the fluid is controlled by the electromagnetic valve 233 by the control unit 201 of the flow rate control apparatus 200. This process flow is for a relatively short period of time so that it is not necessary to consider changes in the ambient temperature T.

  i) When control is started, the control unit 201 first detects the current pressure of the fluid (that is, the pressure at the start of control) P by the pressure sensor 231 as shown in step S1 of FIG. In this example, it is assumed that the pressure at the start of control is P = 300 mmHg.

  ii) Next, the control unit 201 changes the drive voltage V of the solenoid valve 233, detects that the fluid has started to flow through the solenoid valve 233 by the flow sensor 232, and detects the start of the fluid flow. The drive voltage is obtained as the flow start point voltage Vs (step S2 in FIG. 10). In this example, it is assumed that the flow start point voltage Vs is 3.10 V as in the example indicated by the broken line A1 in FIG. In addition, the change of the drive voltage V at this time is performed in the vicinity of the flow start point voltage Vs toward the flow start point voltage Vs from the high voltage side where the solenoid valve 233 blocks the fluid. That is, the change of the drive voltage V is performed at a position sufficiently away from the limit voltage Vf (in this example, from about 1.4 V to 0.8 V).

iii) Next, as shown in step S3 of FIG. 10, the control unit 201 correlates the sample electromagnetic valve stored in the correlation storage unit 251 according to the flow start point voltage Vs of the electromagnetic valve 233 ( In this example, the limit voltage Vf at which the electromagnetic valve 233 is fully opened is converted and obtained using the equation of the line segment RL ₃₀₀ representing the correlation shown in FIG. In this example, since the flow start point voltage Vs is 3.10 V, the limit voltage Vf of the electromagnetic valve 233 is obtained as 1.10 V as indicated by a broken line A2 in FIG. As described above, the limit voltage Vf can be obtained without detecting the ambient temperature T.

  iv) Next, as shown in step S4 of FIG. 10, the control unit 201 sets the drive voltage V of the electromagnetic valve 233 within a range (effective setting range) between the flow start point voltage Vs and the limit voltage Vf. The flow rate Q of the fluid is controlled. At this time, the effective setting range is set to 3.10V to 1.10V, and the flow rate Q of the fluid is controlled.

Specifically, the control unit 201 detects the current flow rate Q by the flow rate sensor 232 and obtains a difference (Q−Q _TARGET ) between the current flow rate Q and the target flow rate Q _TARGET . And the drive voltage V which should be applied with respect to the solenoid valve 233 (the solenoid coil 279) is calculated so that this difference may become zero. Here, when the drive voltage (referred to as V _CALC ) calculated by the control unit 201 is outside the effective setting range 3.10V to 1.10V, for example, V _CALC = 1.05V, the control unit 201. The drive voltage V is corrected to, for example, 1.15 V in the vicinity of the limit voltage Vf within the effective setting range (0.05 V is provided as a margin for the limit voltage Vf). The drive voltage V set in the effective setting range by the control unit 201 in this way is applied to the electromagnetic valve 233 by the duty calculation unit 202, the pulse generation unit 203, and the valve drive circuit 230 in FIG. Thereby, feedback control is performed so that the flow rate Q of the fluid becomes the target flow rate Q _TARGET .

  As described above, in this flow control device 200, the drive voltage V of the solenoid valve 233 is set effectively because the limit voltage Vf at which the solenoid valve 233 is fully opened is calculated using the correlation of the sample solenoid valve. It can be set accurately within the range.

v) Thereafter, as shown in step S5 of FIG. 10, unless the pressure P detected by the pressure sensor 231 changes (NO in step S5), the control in step S4 is continued at a constant cycle. The presence or absence of a pressure change is determined by the difference (absolute value, ie, | P-P _PREV |) between the pressure detected immediately before (this is P _PREV ) and the current pressure P as a threshold (this is α). (For example, α = 10 mmHg). At the start of control, the current pressure P detected by the pressure sensor 231 is set as P _PREV .

vi) On the other hand, if the pressure P detected by the pressure sensor 231 changes (YES in step S5), that is, if | P-P _PREV |> α, as shown in step S6 of FIG. Is obtained by converting the current starting point voltage Vs and the limit voltage Vf corresponding to the current pressure P for the solenoid valve 233.

FIG. 11 schematically shows how the current flow start point voltage Vs and the limit voltage Vf are converted and obtained when the pressure P detected by the pressure sensor 231 changes. FIG. 11 shows a point D1 corresponding to Vs = 3.10V and Vf = 1.10V at the start of control in the line segment RL ₃₀₀ shown in FIG. 8, and a line segment RL ₁₅₀ shown in FIG. A point D2 corresponding to D1 is shown. Moreover, the shift of Vs and Vf from the point D1 to the point D2 when the pressure P changes from 300 mmHg to 150 mmHg is represented by a vector B1.

Here, it is assumed that the current pressure P takes a value Px (unit: mmHg) between 300 mmHg and 150 mmHg to which the correlation stored in the correlation storage unit 251 is given, for example. At this time, a ratio (300 mmHg−Px) / (300 mmHg−150 mmHg) of the following expression (1) is added to the vector B1 (representing the shift of Vs and Vf from the point D1 to the point D2) shown in FIG. 11 (1).
And an internal dividing point Dx between the points D1 and D2 is obtained by an interpolation method. In the example of FIG. 11, the internal dividing point Dx has a flow start point voltage Vs = 2.95 V and a limit voltage Vf = 1.10 V corresponding to the current pressure P (= Px) (indicated by broken lines A3 and A4 in FIG. 11). .).

  In this way, when the pressure P detected by the pressure sensor 231 changes, the current start point voltage Vs and the limit voltage Vf can be converted and obtained.

  When the current pressure P is greater than 300 mmHg or less than 150 mmHg, an external dividing point (not shown) is obtained by extrapolation, and the flow start point voltage Vs and limit voltage Vf represented by the external dividing point are obtained. You may ask for it. Or you may memorize | store the correlation which covers such a pressure P in the correlation memory | storage part 251 beforehand, and may obtain | require by the interpolation method.

  vii) Next, the control unit 201 returns to step S4 in FIG. 10 to change the drive voltage V of the electromagnetic valve 233 to the flow start point voltage Vs (= 2.95 V) corresponding to the current pressure P and the limit voltage Vf (= The flow rate Q of the fluid is controlled within a range between 1.10V) (current effective setting range).

  Thereafter, the control unit 201 repeats the processes of steps S6 and S4 every time the pressure P detected by the pressure sensor 231 changes (YES in step S5). Thereby, even when the pressure P of the fluid changes during the control period, the drive voltage V of the electromagnetic valve 233 can be set accurately in real time within the effective setting range.

In the above example, the pressure at the start of control is set to P = 300 mmHg in step S1 of FIG. 10, but is not limited thereto. When the pressure P at the start of control takes a value between 300 mmHg and 150 mmHg (this is assumed to be Py), for example, the expressions of the line segment RL ₃₀₀ and the line segment RL ₁₅₀ stored in the correlation storage unit 251 As shown in FIG. 12, an equation of a line segment RL _Py representing the correlation between the flow start point voltage Vs corresponding to the pressure Py and the limit voltage Vf is obtained by interpolation as shown in FIG. For example, shifts from the end points E1 and E2 of the line segment RL ₃₀₀ to the corresponding end points E3 and E4 of the line segment RL ₁₅₀ are represented by vectors B3 and B4, respectively. In these vectors B3 and B4, the ratio of the following formula (2) (300 mmHg−Py) / (300 mmHg−150 mmHg) (2)
And an internal dividing point Dy between the points E1 and E3 and an internal dividing point Dy 'between the points E2 and E4 are obtained by interpolation. Then, a line segment connecting these internal dividing points Dy and Dy ′ is obtained as a line segment RL _Py representing a correlation between the flow start point voltage Vs corresponding to the pressure Py and the limit voltage Vf. Thereafter, in step S3 in FIG. 10, the limit voltage Vf at which the electromagnetic valve 233 is fully opened is converted according to the flow starting point voltage Vs of the electromagnetic valve 233 using the equation of the line segment RL _Py representing this correlation. Ask. For example, as indicated by broken lines A5 and A6 in FIG. 12, if the flow starting point voltage Vs of the electromagnetic valve 233 is 2.85V, the limit voltage Vf of the electromagnetic valve 233 can be obtained as 1.10V. Thereby, even when the pressure P at the start of control takes a value Py between 300 mmHg and 150 mmHg, for example, the drive voltage V of the solenoid valve 233 is within a range between the flow start point voltage Vs and the limit voltage Vf ( Effective setting range) can be set with high accuracy.

  When the pressure P at the start of control takes a value greater than 300 mmHg or less than 150 mmHg, a line representing the correlation between the flow start point voltage Vs corresponding to the pressure P and the limit voltage Vf by the extrapolation method. You may also find the minute expression. Or you may memorize | store the correlation which covers such a pressure P in the correlation memory | storage part 251 beforehand, and may obtain | require by the interpolation method.

  Further, the above-described processing flow is a flow for a relatively short period of time that does not require a change in the ambient temperature T, but is not limited thereto.

For example, in FIG. 11, the line segment RL from the point D1 to the corresponding point D3 when the ambient temperature T changes from 23 ° C. (normal temperature) to 50 ° C. (high temperature) under the condition of the pressure P = 300 mmHg. The shift of Vs and Vf along ₃₀₀ is represented by vector B2. A temperature sensor 234 (shown by a broken line block in FIG. 1) is provided, and a difference (T−) between the temperature detected immediately before (this is referred to as T _PREV ) and the current temperature T (unit: ° C.). T _PREV ) is detected. Whether there is a change in the ambient temperature is controlled according to whether this difference (absolute value, that is, | T−T _PREV |) exceeds a threshold value (this is β, for example, β = 3 ° C.). The unit 201 determines. When the ambient temperature T detected by the temperature sensor changes, that is, when | T−T _PREV |> β, the current start point voltage Vs and the limit voltage Vf corresponding to the current ambient temperature T are obtained for the solenoid valve 233. Calculate by conversion. At the start of control, the current ambient temperature T detected by the temperature sensor 234 is set as T _PREV .

Specifically, the vector B2 shown in FIG. 11 (representing the shift of Vs and Vf from the point D1 to the point D3) is a ratio of the following formula (3) (T-23 ° C.) / (50 ° C.-23 ° C) (3)
And an internal dividing point Dx ′ between the points D1 and D3 is obtained by interpolation. This internal dividing point Dx ′ represents a flow start point voltage Vs and a limit voltage Vf corresponding to the current ambient temperature T (indicated by broken lines A3 and A4 in FIG. 11).

  As a result, even when the ambient temperature T changes during the control period, the drive voltage V of the electromagnetic valve 233 can be accurately set in real time within the effective setting range.

In addition, when the ambient temperature T falls from 23 degreeC (normal temperature), the data from the ambient temperature T in FIG. 8 to 23 degreeC (normal temperature) to 2 degreeC (low temperature) can be used. In that case, instead of the formula (3), the ratio of the following formula (4) (23 ° C.-T) / (23 ° C.-2 ° C.) (4)
Is used.

  When both the pressure P and the ambient temperature T change, the flow starting point voltage Vs and the limit voltage Vf corresponding to the current pressure P and the ambient temperature T are obtained using the combined vector of the vector B1 and the vector B2. Can do. Therefore, even when both the pressure P and the ambient temperature T change during the control period, the drive voltage V of the electromagnetic valve 233 can be accurately set in real time within the effective setting range.

  In the above example, the solenoid valve 233 is a normally open type, but is not limited thereto. The flow control device of the present invention can also be used to control a normally closed type electromagnetic valve. Further, regarding “flow start point voltage Vs” and “limit voltage Vf”, depending on the type of solenoid valve, when flow start point voltage Vs is higher than limit voltage Vf and when flow start point voltage Vs is lower than limit voltage Vf. There is. The flow control device of the present invention can be applied to any of them.

  FIG. 13 shows the appearance of an electronic sphygmomanometer (the whole is denoted by reference numeral 1) according to an embodiment of the present invention. The electronic sphygmomanometer 1 includes a cuff 20 to be worn on the upper arm of a person to be measured, a main body 10, and a flexible tube 38 that connects the cuff 20 and the main body 10. The cuff 20 contains a fluid bag 22 for pressing the upper arm. The main body 10 is provided with a display 50 and an operation unit 52. In this example, the operation unit 52 includes a power switch 52A, a memory switch 52B, and forward / back switches 52C and 52D.

  As shown in FIG. 14, the main body 10 includes a central processing unit (CPU) 100, a memory 51, a power supply unit 53, and a piezoresistive pressure sensor 31 in addition to the display device 50 and the operation unit 52 described above. A pump 32 for supplying air as fluid to the fluid bag 22, a valve 33 for adjusting the pressure (cuff pressure) of the fluid bag 22 (the same as the electromagnetic valve 233 described above), and the pressure sensor 31 Are mounted with an oscillation circuit 310 for converting the output of the output into a frequency, a pump drive circuit 320 for driving the pump 32, and a valve drive circuit 330 for driving the valve 33 (corresponding to the valve drive circuit 230 in FIG. 1). Yes. The pressure sensor 31, the pump 32, and the valve 33 are connected to the fluid bag 22 contained in the cuff 20 through an air pipe 39 provided inside the main body and the tube 38 communicating with the air pipe 39. . Thereby, air as fluid flows between the pressure sensor 31, the pump 32, the valve 33, and the fluid bag 22.

  The display 50 includes a display, an indicator, and the like, and displays predetermined information according to a control signal from the CPU 100.

  In operation unit 52, power switch 52A receives an instruction to turn on / off power supply unit 53 and an instruction to start blood pressure measurement. The memory switch 52 </ b> B accepts an instruction for causing the display device 50 to display the blood pressure measurement result data stored in the memory 51. The forward / return switches 52C and 52D accept a change instruction such as causing the display device 50 to display or advance the display content to the past. These switches 52 </ b> A, 52 </ b> B, 52 </ b> C, 52 </ b> D input an operation signal according to an instruction from the user to the CPU 100.

  The memory 51 stores a program for controlling the electronic sphygmomanometer 1, setting data for setting various functions of the electronic sphygmomanometer 1, and blood pressure value measurement result data. Further, the memory 51 serves as a correlation storage unit for the driving voltage of the sample solenoid valve having substantially the same characteristics as the valve 33 to be controlled, and the flow start point voltage Vs at which the fluid starts flowing through the sample solenoid valve and the sample solenoid valve. The correlation between the fully opened limit voltage Vf is stored. The memory 51 is used as a work memory when the program is executed.

  The power supply unit 53 supplies power to each unit of the CPU 100, the pressure sensor 31, the pump 32, the valve 33, the display device 50, the memory 51, the oscillation circuit 310, the pump drive circuit 320, and the valve drive circuit 330.

  The oscillation circuit 310 oscillates based on an electric signal value based on a change in electric resistance due to the piezoresistance effect from the pressure sensor 31, and outputs a frequency signal having a frequency corresponding to the electric signal value of the pressure sensor 31 to the CPU 100.

  The CPU 100 drives the pump 32 via the pump drive circuit 320 according to the operation signal from the operation unit 52 according to the program for controlling the electronic sphygmomanometer 1 stored in the memory 51, and the valve drive circuit 330. The control which drives the valve 33 via is performed. The valve 33 is opened and closed in order to discharge or enclose the air in the fluid bag 22 to control the cuff pressure. Further, the CPU 100 calculates a blood pressure value based on a signal from the pressure sensor 31 and controls the display device 50 and the memory 51.

  In particular, as shown in FIG. 15 (block configuration of the main part relating to the control of the electromagnetic valve), the CPU 100 adjusts the flow rate of air as a fluid by the valve 33, so that the control unit 201 and the duty calculation unit described above are used. 202 and a pulse generation unit 203 (see FIG. 1), and also functions as a flow rate detection unit 204. As can be seen from FIG. 15, no temperature sensor is provided in this example.

  The flow rate detection unit 204 is based on the volume of the fluid bag 22 contained in the cuff 20 and the change in the cuff pressure (pressure of the fluid bag 22) detected by the pressure sensor 31. (Unit: ml / min) is calculated.

  Note that the air as the fluid that has passed through the valve 33 is discharged to the external environment (at atmospheric pressure) through the fluid outlet 33e of the valve 33.

  FIG. 16 shows a blood pressure measurement flow by the electronic sphygmomanometer 1. This electronic sphygmomanometer 1 measures blood pressure according to a general oscillometric method. In addition, this measurement flow is a flow for a comparatively short time which does not need to consider the change of ambient temperature T. At the time of measurement, a cuff is wound around the measurement site (upper arm in this example) of the subject, and the start of measurement is instructed by an operation by the operation unit 52.

  i) When blood pressure measurement is started, first, the CPU 100 closes the valve 33 via the valve drive circuit 330, and then drives the pump 32 via the pump drive circuit 320, and the cuff pressure P is increased by the pressure sensor 31. While observing, control to send air to the fluid bag 22 is performed. As a result, the fluid bag 22 is inflated and the cuff pressure is gradually increased (step S11). When the cuff pressure is increased and reaches a target pressure (set to be higher than the maximum blood pressure of the subject. In this example, 300 mmHg) (YES in step S12), the CPU 100 passes through the pump drive circuit 320. The pump 32 is stopped.

ii) Next, the CPU 100 gradually decreases the drive voltage V of the valve 33 via the valve drive circuit 330 (step S13), and detects that the air has started to flow through the electromagnetic valve 233 by the flow sensor 232 (step S13). YES in step S14). A drive voltage when the start of the air flow is detected is obtained as a flow start point voltage Vs (step S15). Subsequently, based on the flow start point voltage Vs, the correlation (in this example, the expression of the line segment RL ₃₀₀ representing the correlation shown in FIG. 8) regarding the sample solenoid valve stored in the memory 51 is used. Thus, the limit voltage Vf at which the valve 33 is fully opened is obtained by conversion. Then, the drive voltage V of the valve 33 is set within a range (effective setting range) between the flow start point voltage Vs and the limit voltage Vf, and the air flow rate Q is controlled (step S16). Since the equation of the line segment RL ₃₀₀ stored in the memory 51 includes a relationship when a plurality of ambient temperatures T are set, the limit voltage Vf of the solenoid valve obtained by the CPU 100 corresponds to the ambient temperature T. It will be a thing.

  Thereby, the drive voltage V of the valve 33 can be accurately set in the vicinity of the limit voltage Vf within the effective setting range. Therefore, it is possible to increase the exhaust flow rate at the start of pressure reduction and perform quick pressure reduction. As a result, the time required for blood pressure measurement can be shortened. Further, since the drive voltage V of the valve 33 does not fall below the limit voltage Vf, it is possible to avoid a situation in which the cuff pressure is lowered at a stretch during blood pressure measurement and a measurement error occurs. Moreover, it becomes easy to employ an inexpensive solenoid valve that tends to have a narrow effective setting range.

  iii) Next, while observing the cuff pressure P by the pressure sensor 31, the CPU 100 reduces the cuff pressure P at a target pressure reduction rate suitable for blood pressure measurement. In this depressurization process, the change in the cuff pressure P due to the pulse wave at the measurement site is acquired (step S17).

  iv) Thereafter, the acquisition of the change in the cuff pressure P due to the pulse wave is completed (YES in step S17), or the drive voltage V instructed by the CPU 100 is changed to the limit voltage Vf after the air is completely exhausted from the cuff 20 When it reaches (YES in step S18), the CPU 100 applies a known algorithm by the oscillometric method to the acquired data (change in the cuff pressure P due to the pulse wave) to obtain blood pressure values (systolic blood pressure and diastolic blood pressure). ) Is calculated (step S19). Thereafter, the CPU 100 displays the calculated blood pressure value on the display device 50 (step S20).

  This blood pressure measurement is performed in about one minute so that it is not necessary to consider the change in the ambient temperature T. In addition, the limit voltage Vf of the solenoid valve obtained by the CPU 100 in step S16 described above corresponds to the ambient temperature T. Therefore, the drive voltage V of the solenoid valve can be accurately set within the effective setting range without providing a temperature sensor.

  It should be noted that in the above depressurization process, the CPU 100 may execute a process for obtaining a correlation corresponding to the current cuff pressure P by an interpolation method (corresponding to step S6 in FIG. 10) in real time. In such a case, the flow starting point voltage Vs and the limit voltage Vf corresponding to the pressure at that time can be obtained in real time by conversion. Therefore, the drive voltage V of the valve 33 can be set with high accuracy in real time within a range (effective setting range) between the flow start point voltage Vs and the limit voltage Vf.

  Also, in applications where measurement is continued for a long period of time, such as when measuring blood pressure for 24 hours, both pressure P and ambient temperature T may change during the control period. In such a case, it is desirable to further include a temperature sensor to measure the ambient temperature T of the valve 33. Thereby, conversion using the combined vector of the vector B1 and the vector B2 shown in FIG. 11 is performed, and the flow start point voltage Vs and the limit voltage Vf corresponding to the current pressure P and the ambient temperature T can be obtained. . Therefore, even when both the pressure P and the ambient temperature T change during the control period, the drive voltage V of the valve 33 can be set accurately in real time within the effective setting range.

  The above-described embodiments are merely examples, and various modifications can be made without departing from the scope of the present invention.

1 Electronic Sphygmomanometer 20 Cuff 22 Fluid Bag 33 Valve 51 Memory 100 CPU
200 Flow Control Device 201 Control Unit 233 Solenoid Valve 251 Correlation Storage Unit

Claims (7)

A flow rate control device that controls the flow rate of fluid by opening and closing a solenoid valve with a drive voltage,
A flow rate detection unit for detecting the flow rate of the fluid flowing through the solenoid valve;
For a sample solenoid valve having substantially the same characteristics as the solenoid valve, the correlation between the starting point voltage at which fluid starts flowing through the sample solenoid valve and the limit voltage at which the sample solenoid valve is fully opened is stored. A correlation storage unit;
When starting the control of the flow rate of the fluid, the drive voltage of the solenoid valve is changed, and the drive voltage when the flow rate detection unit detects the start of the flow of the fluid is obtained as a flow start point voltage. Based on the flow start point voltage, using the correlation for the sample solenoid valve, after converting the limit voltage at which the solenoid valve is fully opened, the drive voltage of the solenoid valve is calculated as the flow start point voltage. A flow control device comprising: a control unit that is set within a range between the limit voltage. The flow control device according to claim 1,
The flow rate control apparatus according to claim 1, wherein the correlation of the sample solenoid valve stored in the correlation storage unit includes a relationship when a plurality of fluid pressures are set. In the flow control device according to claim 2,
A pressure sensor for detecting the pressure of the fluid;
The control unit
At the start of control, the pressure of the fluid is detected by the pressure sensor,
When the pressure of the fluid at the start of control takes a value other than the plurality of pressures giving the correlation stored in the correlation storage unit, based on the correlation corresponding to the plurality of pressures, By interpolating or extrapolating, obtain the correlation between the flow start point voltage corresponding to the pressure of the fluid at the start of control and the limit voltage,
The flow rate control apparatus characterized by using the obtained correlation when the limit voltage is obtained by conversion based on the flow start point voltage of the solenoid valve. In the flow control device according to claim 3,
The control unit
Detecting the current pressure of the fluid by the pressure sensor during the control period;
When the current pressure of the fluid changes from the pressure at the start of control, the current flow starting point voltage and the limit voltage for the solenoid valve are converted and obtained based on the correlation corresponding to the plurality of pressures. A flow control device characterized by that. In the flow control device according to any one of claims 1 to 4,
The flow rate control device according to claim 1, wherein the correlation for the sample solenoid valve includes a relationship when a plurality of ambient temperatures are set. The flow control device according to claim 5,
A temperature sensor for detecting the ambient temperature of the solenoid valve;
The control unit
The current ambient temperature of the solenoid valve is detected by the temperature sensor during the control period,
When the current ambient temperature of the solenoid valve changes from the ambient temperature at the start of control, the current flow start point voltage and the limit voltage for the solenoid valve are calculated based on the correlation corresponding to the plurality of ambient temperatures. A flow rate control device obtained by conversion. A cuff to compress the measurement site;
A solenoid valve for adjusting the pressure of the cuff;
A sphygmomanometer comprising the flow control device according to any one of claims 1 to 6.

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